This invention relates to a refrigerant system that may be utilized for operation in both a heating and cooling modes, and wherein an economizer cycle is provided in both modes with a pair of reversing valves to properly route the refrigerant.
Refrigerant systems provide cooled air in an air conditioning mode and a heated air in a heat pump mode. In a standard heat pump without an economized cycle, there is a single four-way reversing valve installed next to a compressor discharge port. Essentially, the refrigerant flow through the system is reversed to provide the two distinct modes. When in a cooling mode, the valve adjacent to the compressor routes the refrigerant from the compressor discharge port into an outdoor heat exchanger and from an indoor heat exchanger into compressor suction port. In a heating mode, this valve routes this refrigerant from the compressor discharge into the indoor heat exchanger and from the outdoor heat exchanger into compressor suction port.
One modern development in refrigerant cycles is the inclusion of an economizer cycle. An economizer cycle taps a portion of a refrigerant flow downstream of the outdoor heat exchanger in cooling mode or downstream of the indoor heat exchanger in heating mode. The tapped refrigerant is used to subcool the main refrigerant flow. The tapped refrigerant passes through an expansion device, where its temperature is reduced during the expansion process, and then through an economizer heat exchanger. In the economizer heat exchanger, the tapped refrigerant exchanges heat with the main refrigerant flow. The tapped refrigerant is then returned to an economizer port of the compressor after having cooled the main refrigerant flow.
While economizer cycles are known in dedicated air conditioning cooling systems, and have been proposed for operation in heating mode of heat pump systems, there have been no effective solution for heat pump systems that successfully incorporate an economizer cycle that can be used in the same system during either cooling or heating mode of operation.
A pair of valves control the flow of refrigerant through the refrigerant cycle, and through the components in an economizer cycle. Preferably, four-way reversing valves are used, although other valves come within the scope of this invention.
The first valve controls the flow from and to the compressor, routing the refrigerant initially from the compressor discharge port, either to the outdoor heat exchanger (cooling mode) or to the indoor heat exchanger (heating mode). This valve also controls the return of refrigerant back to the compressor, routing the refrigerant into compressor suction port from the indoor heat exchanger (cooling mode) or from the outdoor heat exchanger (heating mode). In this invention, a second four-way reversing valve is added to the system. This second valve selectively controls the flow of the refrigerant at a point intermediate of these two heat exchangers, such that the refrigerant flows serially to an economizer heat exchanger and a main expansion device. Further, an economizer tap is provided with an economizer expansion device where this second valve also controls the flow of a tapped refrigerant through the economizer heat exchanger and into a compressor economizer port. The second four-way reversing valve is thus positioned to control and route the refrigerant flow in the appropriate direction to provide the economizer cycle when the system is operating either in cooling or heating mode.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.